PHYSICALand LITERARY. 301 



flrudion of the brain and fpinal marrow, 

 than is the frequency of the ftrokes of 

 the heart ; snd that, as he had found the 

 nerves continue to be afFeded by opium 

 after the heart is cut out, fo he fuppofed 

 that, after the brain and fpinal marrow- 

 are deftroyed, the veins continued to ab- 

 forb the opium, and mix it with the 

 blood, and that the heart continued to 

 circulate it through the body. Whereas, 

 I find, by the afEflance of the microfcope, 

 what indeed I fufpe(5ted to be the cafe, 

 that, although the heart adls even more 

 frequently than is natural to it immedi- 

 ately after deflroying the brain and fpi- 

 nal marrow, and continues for nine or ten 

 hours to contra^, half as frequently as in 

 health j yet its force is inftantaneoufly fo 

 extremely impaired, that the blood in the 

 fmallvefTelsceafes from motion. And 1 have 

 further found, by other experiments, that 

 in the frog the abforption becomes very 

 inconfiderable when the circulation ceafes. 

 So that Dr Whytt's experiments, from 

 which he attempts to determine how far 



frogs 



